黑龙江省东部洋灰洞子铜矿床成矿流体研究

The Research on Ore-forming Fluids of Yanghuidongzi Copper Deposit in Eastern Part of Heilongjiang Province

洋灰洞子铜矿位于黑龙江东部,为兴蒙造山带东端少有的早侏罗纪斑岩型铜矿床。为研究成矿流体的性质及元素沉淀机制,运用显微测温、激光拉曼探针技术,对不同矿化阶段石英内的流体包裹体进行系统研究。实验结果表明:1)流体包裹体类型主要为气液两相包裹体、纯气相包裹体、纯液相包裹体,少量的含子晶多相包裹体;2)均一温度为116～417℃,成矿流体盐度为0.87～15.35wt%(NaCl),密度为0.56～0.97g/cm^(-3);3)流体包裹体气体成分主要为H_2O、CO_2,少量的CH_4、H_2S、N_2。研究结果表明初始成矿流体为中高温、中低盐度、低密度、还原性深源岩浆水,成矿过程中流体发生沸腾作用,晚期有大气水的混入。结合矿床地质特征认为该矿床为还原型斑岩铜矿。

The Yanghuidongzi copper deposit is located in eastern part of Heilongjiang Province,and represents one of the few known Early Jurassic porphyry Cu deposits within the eastern edge of the Xing'an–Mongolia Orogenic Belt.The fluid inclusions in Quartz have been investigated by using microthermometric measurements and Raman microprobe to study ore-forming fluid and precipitation mechanism.Results have shown that:1)The type of fluid inclusion mainly includes aqueous-biphase fluid inclusions,mono-phase vapor fluid inclusions,mono-phase liquid fluid inclusions and a few of daughter-bearing fluid inclusions;2)homogenization temperatures range from 116℃to 417℃;the salinities and densities in the whole mineralization process are between 0.87 wt%(NaCl)and 15.35 wt%(NaCl),and 0.56~0.97 g/cm-3,respectively;3)The compositions of the volatile are mainly H2 O,CO2,and a little of CH4,H2 S,N2.Theresults show that the initial ore-forming fluids are characterized by intermediate-high temperature,low-intermediate salinity,reductive magmatic water in deep;the metallogenic mechanism is fluid boiling,and meteoric water was involved in the late mineralization stage.Combined with ore-geology characteristic,Yanghuidongzi copper deposit is regarded as reduced porphyry Cu deposit.